Ping Labz (Page 10)

eBGP vs iBGP: What's the Difference and When to Use Each

eBGP and iBGP look similar at a glance but behave very differently around TTL, next-hop, AS-path, and route advertisement. Treating them as the same protocol gets you in trouble fast; here are the rules.

4 min read Mar 28, 2026

BGP public

How BGP Works: Peers, Updates, and the Finite State Machine

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BGP peering does not auto-discover. Every session is deliberately configured, runs over TCP port 179, and walks a strict finite state machine before a single route flows. The foundation you need before touching BGP config.

4 min read Mar 28, 2026

BGP public

What Is BGP? The Protocol That Runs the Internet

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Every time you load a webpage, your traffic crosses networks owned by different organizations. BGP, the Border Gateway Protocol, is what stitches 75,000+ autonomous systems into a single working internet. Here is how, and why.

3 min read Mar 28, 2026

BGP public

BGP Route Filtering with Prefix Lists

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Prefix lists are the preferred BGP filtering tool: faster than ACLs, easier to read, and built for matching networks with specific prefix lengths. Every production BGP deployment needs them on inbound and outbound.

5 min read Mar 28, 2026

BGP public

BGP Confederations: An Alternative to Route Reflectors

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BGP confederations scale iBGP by dividing the AS into sub-ASes that speak confederation eBGP internally, while appearing as a single AS to the outside world. An alternative to route reflectors with tradeoffs you need to know.

3 min read Mar 28, 2026

BGP public

BGP Route Reflectors: Eliminating the Full Mesh

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Ten routers need 45 iBGP sessions. Fifty need 1,225. Route reflectors break the iBGP split-horizon rule in a controlled way, and are the standard scaling tool for iBGP in enterprise and service provider networks.

4 min read Mar 28, 2026

BGP public

BGP Next-Hop-Self: When and Why You Need It

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One of the most common iBGP problems is routes that show up in the BGP table but never hit the routing table because the next-hop is unreachable. Here is when next-hop-self is the fix, and when it actually makes things worse.

4 min read Mar 28, 2026

BGP public

How to Configure iBGP Neighbors and Full Mesh

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iBGP has rules eBGP does not: split-horizon, full-mesh, and next-hop preservation. Ignore any of them and routes vanish silently from your network. A practical guide to configuring iBGP neighbors and full mesh.

5 min read Mar 28, 2026

BGP public

How to Configure eBGP Neighbors on Cisco IOS XE

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A single mismatch in neighbor IP, AS number, or filtering keeps a BGP session down without a helpful error. A practical Cisco IOS XE eBGP configuration walkthrough including dual-homed peering and source/TTL considerations.

5 min read Mar 28, 2026

BGP public

How BGP Advertises Routes: NLRI, Withdrawn Routes, and the Adj-RIB

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BGP does not auto-advertise connected interfaces like OSPF. Routes must be injected via network, redistribution, or aggregation. Understand NLRI, withdrawn routes, and the Adj-RIB pipeline to control what you advertise.

4 min read Mar 28, 2026

BGP public

BGP Best Path Selection Algorithm — All 13 Steps

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Cisco BGP picks the best path with a 13-step algorithm. Most real decisions resolve in steps 1 to 5, but troubleshooting unexpected path selection means knowing every step. A complete walkthrough with examples.

5 min read Mar 28, 2026

BGP public

BGP Session Authentication: MD5 and TCP-AO

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An unauthenticated BGP session is vulnerable to TCP-based attacks and spoofed RSTs. MD5 has been the standard for decades; TCP-AO is the modern replacement. A practical guide to BGP session authentication.

4 min read Mar 28, 2026